| 摘要 |
PROBLEM TO BE SOLVED: To suppress the excessive increase of the temperature of a waste heat recovery boiler inlet duct and the excessive increase of the steam temperature of a superheater outlet. SOLUTION: In a waste heat recovery boiler 7 where in a superheater 8, a vaporizer 9, and an economizer 10 are arranged in this order, along a flow of combustion exhaust gas, a duct burner for reheating boiler water is installed at the inlet of each of the superheater and the vaporizer. A combustion amount at a superheater inlet duct burner 4 is regulated based on the inlet exhaust gas temperature and a superheater outlet steam temperature 13 of the waste heat recovery boiler. A combustion amount at a vaporizer inlet duct burner 5 is regulated based on a saturated steam amount 14. alternatively, arrangement of the super heater 8 and the vaporizer 9 at a passage for a exhaust gas flow is reversed and a boiler inlet, the vaporizer, the superheater and the economizer are installed in this order, and the duct burner is installed at the inlets of the vaporizer and the superheater.
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